The LIFEPAK 5.RTM. monitor and defibrillator produced by Physio-Control Corporation of Redmond, Wash., is a multicomponent medical instrument having an EKG monitor and a defibrillator. The monitor records and analyzes a patient's EKG signal while the defibrillator produces a high energy defibrillation pulse to terminate ventricular or atrial fibrillation. The LIFEPAK 5.RTM. monitor and defibrillator can be secured together as a single unit, having both monitoring and defibrillation capability. Alternatively, each component may be used separately when only one function is desired. Details of the interconnection are described in U.S. Pat. Nos. 4,096,856 and 4,097,113, which are expressly incorporated by reference herein.
When the two components of the LIFEPAK 5.RTM. are interconnected, five electrical contacts in the form of vertically spaced and horizontally extending leaf springs on the monitor are engaged by five corresponding contacts on the defibrillator. The top two contacts are used to transmit EKG data received from the defibrillator's hard paddles to the monitor. The center contacts are connected to isolated ground. The bottom two contacts are dedicated to operation of the instrument in a "synchronized cardioversion mode" in which the EKG monitor analyzes the EKG data from the top contacts or other EKG input and transmits a "sync pulse" to the defibrillator by way of the bottom contact when an R wave in a QRS complex is detected. The defibrillator signals the monitor that synchronized cardioversion mode is selected by applying a D.C. voltage signal to the contact immediately above the bottom sync pulse contact. Upon receipt of a sync pulse, the defibrillator delivers a defibrillation pulse to the patient.
While the LIFEPAK 5.RTM. constituted an advance in the field of separable medical components that could be used separately or interconnected to function cooperatively, the interchange between the units was quite limited.